I know this is an *old* post, but did you ever determine that you did need a new bipolar PROM burned for your lamp sequencer? I've got a suitable programmer, I think I have the bit image somewhere, and probably even have a blank 82S123. It seems to me there is a clock on the board (possibly a 555) - is that running?

FYI - I've also created a "satellite" PC board that goes in place of the lamp driver transistors that uses higher current SMT darlingtons in their place. Remove the 2222's and solder the satellite board in place, and it's good to go.

The satellite board worked really well, but it hasn't had many hours put on it so far either. The runtime so far has been limited to the time it spent running in the shop, and it running in "Flynn's Arcade" in Vancouver